Organizations such as on-line retailers, Internet service providers, search providers, financial institutions, universities, and other computing-intensive organizations often conduct computer operations from large scale computing facilities. Such computing facilities house and accommodate a large amount of server, network, and computer equipment to process, store, and exchange data as needed to carry out an organization's operations. Typically, a computer room of a computing facility includes many server racks. Each server rack, in turn, includes many servers and associated computer equipment.
Because the computer room of a computing facility may contain a large number of servers, a large amount of electrical power may be required to operate the facility. In addition, the electrical power is distributed to a large number of locations spread throughout the computer room (e.g., many racks spaced from one another, and many servers in each rack). Usually, a facility receives a power feed at a relatively high voltage. This power feed is stepped down to a lower voltage. A network of cabling, bus bars, power connectors, and power distribution units, is used to deliver the power at the lower voltage to numerous specific components in the facility.
A computing facility may receive one or more power feeds from one or more external power sources. For example, a power feed may originate from a utility power source. The power feed originating from a utility power source may be passed along power transmission lines at a high voltage (e.g., 115 kilovolts) to an electrical substation, which may include a transformer that can step down the power feed voltage to a lower voltage and supply the power feed to the computing facility. Power feeds may be stepped down by a substation transformer to a low voltage (e.g., 480 volts) or a medium voltage that is distributed to additional transformers to be stepped down further to a low voltage.
From time to time, a power feed from an external power source may experience disturbances that may interrupt normal receipt of power at the computing facility. For example, a lightning strike may cause a brief fluctuation in the power feed received at the facility. In another example, the power feed may become unstable such that it becomes unusable by the facility. In another example, an unexpected fluctuation in a power feed may damage downstream electrical equipment. In a further example, a power feed may fail altogether.
In many cases, a computing facility may include a low-voltage backup power source that can temporarily supply backup power to the facility in the event that a power feed from an external power source is lost. For example, a facility may include a generator powered by a diesel engine, where the generator is activated if the primary utility power feed is lost. A computing facility can include an uninterruptible power source (UPS), such as a battery, which can provide an uninterruptible supply of power for a short period of time.
A backup generator can require time to be activated and readied to supply backup power, which may present difficulties for a facility where even a brief interruption of power can damage equipment or otherwise interrupt normal operations. Furthermore, a backup generator may be expensive to operate. For example, a diesel-fueled backup generator may consume significant amounts of diesel fuel over a period of time, and the generator may require additional maintenance to maintain a reliable backup capability
In many cases, a computing facility may be charged a variable rate by utility providers for electric power provided to the facility. For example, a price per kilowatt-hour of electricity consumed at a computing facility may vary throughout a day or throughout a year based on overall market demand such that the computing facility pays significantly higher costs per kilowatt-hour of electricity consumed during peak times of day or seasons of the year. Also, in many cases utility providers may charge a computing facility a demand charge based on peak flows of electrical power to the computing facility. For example, a demand charge may be based on the highest recorded electrical flow in kilowatts occurring during 15-minute increments throughout a day. A computing facility may be charged both demand charges for the highest flows during a day (kilowatts) and may be charged for consumption (kilowatt-hours).
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include,” “including,” and “includes” mean including, but not limited to.